Switching mechanism



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Jan. 8, 1929.

J. ERICKSON swI'rcHING MEcHANIsM 5 Sheets-Sheet 2 Original Filed Sept. l1, 1925` Inuen D1" .Jahn Ezlcksm l Err-N Jms,1929 v 1,698,126

' J. ERICKSON SWITCHING MECHANISM A Original Filed Sept. 11, 1925 5 YSheets-Sheet 5 Jan. s, 1929. I1,698,126

1. ERICKSON l .1m s, 1929. I*

J. ERICKSON SW1 TCHING MECHANI SM original Filed sept. 11, 1925 5 sheets-sheet. 5

Patented Jn. s, 1929.

UNITED STATI-:s

, I -A 1,693,126 Ol-FI'CE.

JOHN ERICKSON, or CHICAGC, ILLINOIS, AssIGNoa, BYl rIEsNE ASSIGNMENTS, 'ro

AUTOMATIC ELECTRIC INC., or CHICAGO, 'ILLINoIsjA lconroaxrIoN or vmima- WARE.

SWITCHING M E'CIIANISM.-

Application mea september' 1I, 1925, .serial No. 55,689. 'ne-awed :une c, 192s.

The'pre'sent invention", broadly stated, re-

. latesto. switching mechanisms used in automatic telephone systems. More particularly,

my invention lis concerned with improvements applied to switches of the Well known vertical and rotary type as disclosed .in the U. S.

patents to Keith, Erickson, and Erickson,

I Nos. 815,176 and 815,321, both granted March A brief account of the objects of my invention with reference to the mechanisms disclosed in the above patents shall irstbe given so that the detailed description which is to follow maybe readily understood and fully' appreciated. In view of the. fact that the apparatus is well known, it is thought to be unnecessary to go into minute detail of its functions. Accordingly, I shall limit myself to the description of operations only which are necessary for the comprehension of my-in. vention.

Referring now to the. operation of the' n switching apparatus disclosed in the patents cited above, a shaft carrying a.l number of wipers will first be raised in a-vertical direction, positioning the Wipers opposite a certain level or row of contacts. The shaft will then be rotated horizontally until the wipers are brought into engagement with a certain set of contacts representing either an idle trunk or a called line. Considering particularly the rotary operations', it will be seen' that a relatively great amount of friction caused by the wipers brushing over the con- Cil tacts must be overcome by a magnet executing the step by step rotary movement. This friction does not` only result in unnecessary wear and tear ofthe various'parts,'such as the wipers, the bank contacts, and the pawl operated by the armature of the'rotary magnet and forcing itself into the jteeth of the rotary ratchetI cylinder on the switchshaft, butit also necessitates a powerful magnet and limits the speed of the'operation toa deiiv nite point beyond which a safe and positive action cannot be accomplished. In other Awords, the speed of the switch mechanismis largely depending on its ,mechanical con'- struction.

It is, however,.a well known fact that the/V mechanism in setting up a connection., is one of the vital factors in the operation of automaticv telephone systems. Speed and mechanical is evident that a reduction of friction must l benefit the 'problem of speedier operation. j One ofthe objectsl of my invention is to reduce the friction between certain movingparts participating in the rotary motionof the switch without impairing their positive functions.v In a switch, such as I have chosen for illustrating my invention, having two. line and one private wipers, I-eliminate the 'friction of the two line wipers 'entirely and, to 'some extentreduce also the friction of the private wiper. In other words, the line wipers are withdrawn from the bank contacts during the rotary movement, While the rivate wiper touches the private'contacts ]ust sufficiently to warrant safe operation. After the wipers are advanced toa desired set of contacts in a level, they will be forced against the contacts and locked in oper-atedy position electrically or mechanically as will be seen later on from the detailed explanation.

The results of this arrangement'are obvious. Unclue wear and tear of the parts brought into play during the rotary movement of a switch is eliminated, .which will be reflected in a prolonged service of the apparatus, obviating frequent readjustments and re'- placement 'of worn out parts. In other words, the life cfa switch will be increased. .I

`Apart from this gain, which in itself is high- VsesY ly desirable, I am also enabled to utilize the power formerly used for subduing'mechanidesired for'some reason or other, the advantages of my improvements may be realized in some other .form which readily suggests itself, for example, by employing aweaker rota-ry magnet as was formerly necessary for attaining the same results, thus reducing the A initial cost of the switch and also o erating expenses. Although the saving might ap- 1 Y pear to be negligible if only one switch is considcred, it will be perceived at once that a.' decided gain will result in com lex systems using a'great number of switcll stances running into thousands.

Another objectof my invention'hasmore I particularly to do with the Amaintenance of the switching apparatus. Although this es, in some inios problem .is inherently afected by the i1n provements'intimated in theforegoing paragraphs, it being evident that a mechanismsub]ected to but a minimum amount of wear friction being in a relation of reciprocity, it will need only a minimum amount of care 11,0

and supervision, I also employ an improved and simplified arrangement of bank contacts and simplied wipers, cheap in manufacture, reliable in operation and reducing the possibility of trouble caused by external forces, human and otherwise, to a minimum.v

Referring to the arrangement of bank contacts, .it will be rememberedV that inthe usual switches the private contacts are located in a bank and arranged in rows, each row containing but single contacts, while the line contacts corresponding to the respective private rows are arranged in a separatebank, also in rowsor levels, each level, however, containing double as many line contacts as there are private contacts and arranged in pairs. To elucidate this point in order to vividly recall the usual arrangement of the bank contacts, if ten lines'were located in a 'certain level, the private row would contain the ten private contacts arranged in physical sequence, while the row in which the line contacts are located, would contain twenty contacts, each line or trunk being composed of two'conductors. The two contacts comprising a line or trunk are in the usual arrangement, positioned opposite each other and separatedby an insulator.

' This arrangement, although it proved satisfactory through long established use, has a number of inherent faults. In the rst place, the manufacture of the line bank is extremely expensive due to the fact that pairs of contacts must be arranged, insulated from one another and rigidly fixed in place in accordance with their corresponding contacts in the private bank which requires a more compli- .catedv process and more skill than the assembling of Asingle contacts in sequence. Secondly, there is an inductive iniiuence between the contacts, which, in eifect, represents a capacitance bridged across the line l or trunk and which can only be reduced to a permissible maximum by the use of heavy partitions made from high grade insulators.

-Thirdly, there is the problem of preventing accumulation of dust upon the contacts. The deteriorating effect produced is, however,

less the amount of dust the contacts collect in the course of time, but more so its unequal i protected by their location undernearth the partition, will, insome instances be almost wholly dust free, while the upper row exposed as itis, 'is pre-eminentlyitted to provide for read dust collection. Thus, conditions not on y contribute towards unequal y the lower wiper will be less subjected to wear,

wear of the wipers and contacts as the upper line wiper, during rotation, will scrape the dust and grind over the contacts, while but the'contacts of the-upper row will after some time be covered with a solid crust of dust particles, greatly affecting the eiiiciency of the apparatus; vThe numerous defects resulting from those conditions may be temof the. wipers, but it will be apparent that such readjustments, however skillfully applied, will only add to future troubles.

To overcome the objectionable features which I have picked at random and intimated above, I propose, in accordance with one of the objects of my invention, to arrange the line contacts in a similar manner as is done in case of the private contacts, viz, in a physical sequence and not in pairs. This, of course, necessitates a modification of the two line wipers. It will be seen presently, that I have modified and simpliiied the line as well as the private wipers. By way of preliminary explanation, I may state that the wipers advance underneath the contacts in a certain row, the line wipers not touching the contacts, While the private wiper advances with a slight pressure. The line wipers will be forced against and intoiirm engagement with theline contacts and the tension of the private wiper will be increased after all wipers have been positioned opposite the proper set. In releasing, the line wipers will first be withdrawn from the contacts, and the tension of the private wiper will be lowered to its original value before starting on the ret-urn movementto normal position.

Still another object of my invention resides in a novel operating magnet, i. e., a magnet used for operating the shaft of a vertical and rotary switch, for example. Such magnet which is subjected to momentary heavy loads of current must be provided with protecting means preventing it from burning out in case it should, through some fault, become permanently connected to the current source. There are, of course, supervisory signaling arrangements provided in an automatic exchange which call the attention of an oflice attendant to such emergency. However, the attendant might be otherwise occupied, or the switch may be located in a branch exchange not having an attendant/at all. I have deL vised a magnet capable of withstanding heavy loads for an appreciable length of time without any detrimental results, and I have also improved the efficiency of the magnet by improving its magnetic properties.

l The magnets usually employed for elfectlng the movements of a switch have two separate solid cores each provided with a winding and mounted on a common heel piece. In my lmproved magnet, I use only one lannnated core for reducing eddy currents and `thus preventing excessive heat production in case of a 'permanent connection'. Incidental to combining two cores into one, the total airgap required between the armature and the lcore-lnview of residual vmagnetic forces is reduced as far as the magnetic circuit is c oncerned by one-half of the'air-gap resulting for the magnetic iux 1f two cores are used.

apparatus, and

Legame To explain this point a little further, if two cores are used, a certain air-gap will be adjusted between the armature and the two cores, while the armature is in operated position. The magnetic, circuit between the two cores will therefore be interrupted at two points, viz, the two air-gaps between each ot the cores and the armature. Using only one core, it willbe apparent that I am enabled with my improve magnet, to retain the same air-gap as in the former case, and at the same time reduce the air-gap for the magnetic flux.

As will be seen from the detailed description, the magnet is also provided with 'an adjustable heel piece, comprising two parts'. One of these parts is provided with slots, the other with corresponding threaded holes. The two parts are rigidly held together by means of screws extending through the slots on one part of the heel piece and taking hold in the threaded holes lot the other part. The heel piece is adjusted with the magnet energized and the armature in attracted position.

It will be evident that the movable part of the heel piece will be attracted by the armature, thus closing a. magnetic circuit next to perfect, in which position it will be secured by means of tightening the screws. y Although the principal purpose of the adjustable heel piece is to improve the magnetic properties of the magnet. there are other advantages accruing from this arrangement which will be brought. out as the-description progresses.

From the above somewhat cursory account l of the various objects, it will be apparent,

that' my invention presents several advantages. The novel method of advancing the line lwipers out of engagement with the contacts in a level, reduces the mechanical riction to a minimum, eliminates undue wear of the various parts, increases the reliability of operation, benefits the maintenance of the at the same time increases its eiciency and lowers the operating expenses. The simplified bank contact arrangement and the simplified novel wipers I propose, tend to 'further lower the cost of the mechanism jas by cheapening the processof manufacture and contributingalso toward the advantages enumerated above. The objects and features discussed in connection vwith the. novel magnet also contribute towardreliable operation and utmost efficiency, due to the improved magnetic properties.

I shall now enter a-detailed description of the opera-tions of my invention, which I have shown incorporated in a vwell known switch-- ing mechanism of the vertical and rotary type. l

Referring now to the drawings forming a part of this specificationl Figsl and 2 illustrate the usual and the novel arrangement of bank contacts, respec-v indicating also` Athe relation of the during the rotary operation of the tively, wipers Atacts being arranged switch, or rather to say, just before the rotary operation commences;

Fig. 3 is a. front view of a switch mechanism, with the bank contacts but indicated and details not necessary for a clearvunderstanding omitted. .The switch is shown in normal or non-operated position;

Fig. 4; illustrates the position of the line wipers in normal position, as seen from lines B-B in Fig. 3;

Fig. 5 is trated in Fig. 3, showing also a cross section of the bank contacts;

Fig. 6 illustrates the position of the line wipers in operated position as seen from lines Al-A, Fig. 5; Fig. 7 shows a circuit diagram for use with the switch mechanism disclosed in Figs. 3 and 5;

Figs. 8 and 9 illustrate a preferred forinof carrying out my invention; Fig. 8 showing the relation ot the various parts just before the rotary movement of the switch commences, while Fig. 9 shows the switch in talking position, the line wipers being in engagement with their contacts, and the tension ot the private wiper being increased;

Fig. 10 shows the line wipers used with the switch seen in Figs. 8 and 9 as shown from lines C-C indicated in Fig. 9.

Fig 114 shows a circuit diagram for use with a switch illustrated in Figs. 8 and 9; and j Figs. 12-15, linclusive, illustrate Various views of .the novel operating magnet.

Referring now lparticularly'to Fig. 1, I have shown schematically the usual arrangementot bank contacts. The upper row designated through the numeral 10, contains ten single contacts and represents the private contacts in a certain level, lwhile the lower row, designated 20, contains twenty contacts, arranged in pairs and separatedby a partition 19, represents the corresponding line contacts. The tirst set of contacts 11, 12, and 13 belong, accordingly, to the first line orv trunk in a certain level. The wipers 14, .15, and 16 are shown positioned opposite the level just before the rotary movement commences. It will belobvious that the line contacts'located in the upper part of row 20, Contact 12 being one of them` are exposed and will readily a side vicwlot the switch illuscollect dust, while the cont-acts located underneath the partition 19, including contact 13, are protected from excessive dust collection.- Accordingly, wiper 15 andthe line contacts of the upper row are more subjected to wear thanthe line contacts of the lower'row with all the detrimental result-s discussed in a previousparagraph.

In Fig.'2, I have shown a novel arrangement of the contacts in a level, the line conm'a similar manner as the private contacts. Like parts are, designat-I ed alike and Will be readily recognized without elaborate explanation. It will be lseen that the line contacts in row 2O are arranged in sequence and not in pairs as-usual. thus obviating a partition such as 19 in Fig. 1.

The wipers being of a novel construction which will be described later and .which is best seen in Figs. 4 and 6, are shown 1n a position readyfor commencing with the rot-ary movement. The private wiper 14 will,'ther'e l0 by, brush with slight pressure over the contacts preceding the idle set, in case of a selector having an automatic rotary hunt-ing movement, or preceding the private contact of a wanted'line incase of a connectorin which the wipers are positioned upon the contacts by a directively controlled rotary movement, while the line wipers l5 and 16 are withdrawn from the contacts during rotation and brought into engagement with the proper setonly after they have been positioned, i. e., after the rotary movement is completed.

Summarizing Athe advantages of the arrangement shown in'Fig. 2 over the-one shown in Fig. 1, it will be evident that elimination of the partition togetherl with arranging the contacts in sequence will cheapen the process of production and obviate provisions for the prevention of inductive influence between two contacts; the lower side of the' contacts being protected from dust collection insures safe operation and simplies maintenance, and unequal wear of the contacts and wipers is eliminated. e

Proceeding with vthe description, I shall now explain the operations of the improved 'switch mechanism illustrated in Figs. 3 and 5, having a bank contact; arrangement such as described above and shown in Fig. 2.

The vertical and rotary operations of the switch, shown in Figs. 3 and 5, or rather to say the manner of lifting the shaft in a vertical direction and rotating it in a horizontal plane,

, do not differ from the operations of the usual switch of the vertical and rotary type. lI

v wipers, designated 4 and 5, which are, by means of an arrangement to be presently described in detail, secured to the shaft in a manner adapting them to follow the vertical and rotary movements of theshaft, and to be moved in a vertical upward direction longitudinally to the shaft, independently and in addition to the vertical motion ofthe latter,

and out of their position in `which they are held by spring -7. This latter, additional movement of theline wipers takes place after e' the cessationof the rotary motion, and is effected by the armature 8 of a magnet 9, operati ng arod 10, mounted on the switch framev at points 29 and 30 and having a number of projections, such as 11 at its lower end, not unlike the teeth of a comb. These projections correspond to the various levels. The upper vpart 12 of the U shaped wiper carrier13 will,

from Figs. 3, 4, 5, and 6, Figs. 4 and 6 showing the position of the wipers relative to the contacts and to the rod 10, in normal and in y operated position, respectively, as seen from linesA-A on Fig.4 5 and B-B on Fig. 3,

that the wipers 4 and 5 are' insulated-from each other and also from the carrier 13, by insulators indicated at 14-15 and 16-17,

and mounted upon the lower portion 18 of the carrier 13. The shaft extends through both the lower and the upper portion of the U shaped carrier 13 at points 19 and 20. A clamp 21 having a projection 22, is fastened to the shaft` by means of a screw 23. Projection 22 has riveted-to it alpin 24, which extends through an opening 25 in the upper part 12 of the U shaped carrier 13. spring 7 inserted between clamp U and the lower part 18 of the carrier 13 keeps the latter in normal position with the upper part 12 closely attached to the4 projection 22 of clamp 2 Considering Fig. 4 which shows the normal position of the wipers 4 and 5 relative to rod 10 and to the bank contacts, and re-I calling the vertical operations o f the switch lifting the shaft'up to a desired row or level which operation must be visualized in looking at4 Fig. 4, as taking place vertically to- AWards the observer, it will be seen that the position of the wipers with regard to rod 10 and to the contacts will not be changed during the vertical'. movement of theswitch. The upper part 12, of the carrier '13, however, will with ea'ch step, be positioned opposite a .successive notch of the comb like lower struc- A coiled l ture of rod 10, each notch corresponding to a certain vertical step, or level. VThe wipers,

to follow the step-by-step rotary movement of the shaft, t-hereby advancing the wipers' of Fig. 2.thatfthe private wiper advances.

during the rotary movement slightly pressing against the contacts, while the line wipersy are withdrawn from engagement with the line contacts. It is obvious that the proper relation can' easily be adjusted by means of clamps 8 and 21, respectively. Upon the cessation of the rotaryy movement, i. e., upon the private wiper reaching an idle line in case of the selector, for example, the line wipers will have been positioned underneath 'and opposite the line contacts corresponding to the private contact, but will not be in engagement with them. Magnet 9 energizes at this instant, attracting its armature 8, which 8, which has a projecting lever 27 extending into a groove provided on rod 10 at point 28, will now lift the rod l0. vertically upward,

'. thereby also lifting the wiper carrier 18,

because of the upper portion 12 of the carrier being in engagement-with one of the notches provided at the lower end of' rodl() as .has

, been described.

Ups

The line wipers 4 and 5 mountedon thev carrier, will in this manner be pressed firmly against the proper contactsonly afterV the rotary movement has been completed, and

they will be removed again short-l before the release of the switches which ta res place as usual. Thus the line wipers are in engagement with the line contacts solely whenvneeded for talking or signaling purposes, as the case may be, but withdrawn during the.

setting operation of the switch.

A preferred manner of carrying out my invention is shown in Figs. 8 and 9. The novel features of this modified arrangement, which will be detailed presently, reside in the manner of bringing the line wipers into engagement with the line contacts after they-have been positionedby the rotary movement of the switch. In vthe former case this was effected by means 'of an' additional magnet operating upon the termination of the rptary motion, in the present case, the usual 'vertical magnet will be energized for this purpose, raising the shaft 'by one additional step thus forcing the line wipers into engagement with the line contacts, and at the same time lincreasing the tension of the private wiper. In releasing, the line wipers will irst be with-- 1 drawn from the line contacts, and the tension .construction than the. lilie wipers previousl shown. They will be described now in detai referencebeing-madeto 8, 9, and 10, respectively. It will be seen from these lfigures 'y that the line wipers 7 and 8 are normali restingv against back stops '9 and 10, an held together by. meansof the two mounting plates 11 and 12, but insulated from the mounting plates, and from *each other, by insulators a 13-14- A clamp 15, extending through the mounting plates, is fastenedto the wiper assembly Aand the entire unit is rigidly secured. to. the switch shaftf by a screw 17, attached to the clamp 15.

It will be obvious that both the private wiper and the line wipers can readil be adjusted in their relative positions on tlie shaft with regard to the bank contacts, by simply regulating their positions byV means ofthe clamps 4 and 15, respectively. .'The adjustmentof the-wipers will be in conformance 'to the positions shown in Fig. 8, viz, the private wiper 1 will be adjusted to exercise aslight .pressure upon the private contacts during the rotary' movement of the switch shaft, while the line wipers 7 and 8 'wil1 be withdrawn from the line contacts and advanced between two adjacent rows or levels, underneath the 'row to which they were raised during the ver-` tical movement. At the terminationof the rotary motion, the vertical magnet will receive a current impulse andv liftthe shaft by an additional step, thus completing the connection. ,During conversation the-shaft will 105 shows their posit-ion after the cessation of the rotary step-by step motion, viz, upon the apparatus having seized a desired line or trunk.

Pointing out the differences in mechanical construction between the usual switch and the present one, it will be seen thatv dog 18 is pivoted at point 19 upon an angular holder 20, mounted on the switch frame by means of screws 2l and 33.' tened to the lower part 23 of the'holder 20 and tothe dog 18 at point 24, and holds the dog. 18 in a normal position resting against stop 25 mounted on the switch frame. Dog

-Coiled spring 22 is fas- 18 is located in the usual switch in the same position relative. to the shaft,' but is stationary. The purpose of this. dog is -to guide the switch shaft in its vertical motion, the dog extending into a groove 26 upon the upper 130 an idle trunk in case of a selector havingon top of the'switch shaft.

part 27 of theshaft, as is shown in the pro ]ection above Fi 8. During the rotary'motion the switch s aft will rest on the dog 18 and also on dog 28 as. can also be seen from the projection above Fig. 9, dog 28 being located opposite the guide dog 18 and longi-l tudinally displaced by one vertical step,

while the rotary dog 29, pivotcd, together' with 28 on a common pin 30 which A1s fas-- -tened to the switch'frame by means of aclamp 31, will take .Ahold in the teethof the rotary ratchet. cylinder 32 .and prevent the sha t from rotating back under the tension of'the usual restoring spring mounted in a housing Comparing this arrangement with the mechanicalrdetails of the usual switch it willbe seen that I have merely separated the so called double dog into 'two' parts, 28 and 29,'

an automatic Vhoriz/.ontal hunting motion or. u on being advanced to a wantedline 1n case ci) a connector. The vertical magnet of the switch will now receive an additional `current impulse in a manner to be described later and lift the shaft one additional step. In the usual switch, no additional vertical step could be effected because of the vertical guide dog.

being stationary. In the presentmechanism, however,"l1aving a movable guidedog 18,

the switch shaft will respond to ltheaddi-v tional energization of the vertical ma net and line wipers 7 and 8 will be forced into firm engage-ment with the-line contacts as shown in the drawin Fig 9, while the tension of the private wiper 1 will be increased.

. Dog 28 will thereby take hold in a successive tooth of the vertical vratchet art 27 of shaft 3 thuslocking the shaft meclianically in operated position, while the guide dog 18 will be lifted up on the incline of the obliquely shaped tooth to which it was reviously' engaged, but will be prevented rom engaging vthe next tooth in succession, because-of the surface displacement between the tooth and the front or gripping part ofthe dog. In other words the shaft,l which was supported by both dogs 1.8 and 28, during the rotatin "movement,will now be supported by dog 28 only, and the guide dog 18 will merely rest upon the vertical tooth corresponding to the engaged level, as can easily be seen from the drawlng.

Upon terminating the call, the subscribers Will hang up their receivers and cause thev restoration of the switchi to normal position.

- The release magnet willenergize and attract its armature indicated at 34. The adjustable 'w1 )er 1 is reduced to normal.

pin 35 .attached to the armature ofthe release magnet will thereby strike against the projecting arm 36 oft e upper dog 28, causing it to withdraw from the respective vertical tooth, andallowing the shaft to release vertically by one step. Guide dog 18 takes hold again in the corresponding tooth of the vertical ratchet part 27 and the line wipers 7 and 8 the levels, while the tension of -thevprivate As is.A clearly in icated on the drawing, the arm 36 of dog 28 extends downward overlapping lever 37 which is a projection lof the rotary dog 29. Arm 36 continuing its restoring motion, will accordingly, strike lever 37, which causes the rotary dog 29 to withdraw from engagement with the rotary ratchet cylinder 32. The tension of the restoring spring will be eective now and restore the switch to normal as usual,

assume their normal position between except that the lline wipers are withdrawn from engagement with the line contacts. i

' In Figs. 7 and 11, I have shown, by means of conventional diagrams, circuits to be used v forpoperating the switch mechanisms illus- 'trated in Figs. 3-5 and 89, respectively. As

'these two circuits are practically identical, I shall furnish but one description and shall point out 4the differences in operation whereverthey occur. It should be borne in mind that the differences will appear .upon the switches seizing an idle trunk, as it is assumed that the switches shown are selectors having an automatic hunting movement. In case of the circuit shown in intended for operating the switch mechanism shown in Figs. 3 and 5, the additional magnet designated through the-numeral 90.*will be operated upon the energization of the switching relay 50,' 'while in the circuit shown in Fig.y 7, which is ino 1g.'11, whichk is assumed -to operate with the 4 apparatus illustrated in Figs 8 and 9, the vertical magnet 60 will receive an additional impulse. Referring now to tively, when such selector is seized. (by a line switch or by another selector,as the case may be), the line relay 10, which is connected to the line'conductors 7 and 8 through contacts on the switching relay 50 energizes and closes .a circuit for the release relay 20 from ground through the armature 54 of the switching relay 50.l The release relay 20'energizes and places ground on the release trunk conductor g 9 by means of its armature 21 to maintain the preceding switclrop'erated and to provide a subsequently closed circuit for the switching relay50, which is nowv prepared through the 'I l i I stepping relay 40, by way of interruptor contacts 71 of the rotary magnet 70 and'oif normal contacts 5,the latter bein open at this instant. The release relay 2Ugalso opens a point in the circuit of the release magnet 80 and at the same time prepares a circuit for the vertical magnet 60 at its armature 22.

Figs. 7 and 1,1,.respcclltlA When the calling subscriber dials the neXt digit in the desired number(the first digit. in the case of a first selector) the line relaydeenergizes a number of times corresponding to the digit for which the dial was operated. Upon each deenergization, the line relay 10 opens at its armature 11,the circuit of the release relay 20, but this relay is slow acting and maintains its armatures attracted throughout the series of deenergi'zation. Ass a .furtherresult of each deenergization, the line relay closes a circuit vfor the vertical -magnet 60 through the armature 22 andits working contact by way of the series'relay 30'..

The vertical magnet operates responsive to* the current impulses delivered in this -manner, and raises the wipers of the swltch step by step until they are positioned opposite the desired level of bank contacts. The slow acting series relay energizes in series with the vertical magnet 60 upon the frstimpulse delivered to the latterand it energizes before the shaft is operated through the first step.

j contacts 71 controlled by the rotary magnet.

This is not due to 'an special. adjustment, but merely due to the act that a relay ofthe type used in this case operates more-quickly than the vertical magnetcanzpossibly pull up and lift the shaft. l Upon energizing, the series relay 30 opens a pointv in .the'operating circuit of the rotary magnet 7 O and places a short circuit around'the switching relay 50' by means 'of its armature 3l. The short'circuiting ofthe switching relay-50 serves to prevent its premature .energization-and also to prepare a direct current circuit for the stepping relay40 which is closed as soon as the switchl completes its first Avertical step, this latter circuit includes the interrupter Accordingly, the stepping relay 40 energizes as soon as the ott normal springs 5 close and at armature 41 closes a locking circuit for itself to ground. At its lower armature 42, the stepping relay prepares :a circuit for the rotary magnet 70 which, however, is not com-1- y pleted at this time on account of the fact that the slow acting series relay v3O`is maintained operated throughout the vertical movement.

Shortly after the termination ofthe series of impulses deliveredto the vertical magnet,

. the slow acting series relay 30 deenergizes and 1 .opens the originalcircuit of the stepping re.

lay 40. This latter relay, however, remains locked up and theswitchingrelay 50 remains short circuited to groundat the upper armature 410i the stepping relay. As a further lresult of the deenergization of the series relay l30 a circuit is com leted for the rotary magnet 7 0 from groun at armature 2l by Way of armatures 31 and 42. The rotary magnet 70 energizes and advances the wipers into engagementwith the first set of bank contacts in the level opposite which they were previously raised, Near the end of its stroke, the rotary magnet opens at its'interrupter--contacts 71, l

the circuit of the stepping relay 40. "Responsive to. this' vstepping relay deenergizes and opens at its armature 24 the circuit of the'rotary magnet 70, whereupon the rotary vmagnet deenergizesalso, again closing its interrupter contacts 71;

' From this point the further operations l(lepend upon whether the trunk terminatingin the first set of bank contacts is busy or idle. v If 1t is idle, the switching relay 50- energizes now,o\`ving to `the fact that the short circuit is,

removed from around its winding at the upper armature 41 of the stepping relay 40( As suming', however, that the Vtrunk is busy. the

switching relay 50 is still short circuited bej cause there is a ground potential encountered tthe testcontact of thebusytrunkb'y thetest i w1per2, .and therefore the switching .relay cannot energize. In this case the stepping relayoperatesagaln, this time to ground at the test contact of the busy trunk'by wayofv theg test wiper 2, and again closes its locking cirl cuit and the circuit of the rotary magnet whereupon the latter operates again and 'advancesthe wipers into engagement with the 'Y next set of bank contacts.

This alternate operation continues until an idle trunk is reached, which trunk, itmay be assumed,is the one shown in Athe drawings.'

When this idle trunk is reached, the lswitching relay rbeing no longer short circuited energizes in series with'the stepping relay 40. The stepping. relay, however, cannot opera- Vtively'energize atv this time on account of the high Iresistance of the switching relaygf' Upon. .energlzingg the switching relay 50 removes g ground, at its armature 54. from the amature 11lof the line relay, thereby-opening the circuitof'the slow acting release relay 20; dis'- connects the test iwiperfrom the junction of its own winding and the winding ofthe stepping relay 40, at its armature 52 and connects it instead to the grounded release trunk con-- ductor, thereby also extending ground to the release trunk conductor of the seized switch and making it busyimmediately: and at its upper and lower armatures 51 and 55 disconnects the incoming trunk conductors andY 8 from the upper and lower windings ofthe line relay 10. The further operations ofthe twov switches are soniewhtdierentlandjvillbe'. p

ydescribed separately1-.' f The operations oflthe circuit, Fig. '7, which is' designed to operategwith the switching mechanism shown in'FigstB and 5,shallbeeirl l plained first.v It willbe remembered'that y' said switching mechanism is' provided-with an additional magnet designated through the `numeral 9, which magnet must operate whenever an idletrunk is tested free, for' the purpose of operating the rod 10, which moves the wiper carrier 13, and with it the line wipers t and 5 into engagement with the line contacts. This magnet is'shown in the circuit,

' Fig. 7 and indicated through the nunieral 90.

l' tracts'its armature 53 and closes thereby a i the test wiper 2 thereby extending the incoming lineconductors to the corresponding con-- The switching relay 50 in addition to its various functions, explained above, also at circuit for magnet 90. Wipers l and 3 will be forcedup and against the line contacts cor-l responding to the private contact engaged by du'ctors bf the seized trunk line.

' Referring to Fig. 11, which operates in connectionwiththe switch shown in Figs. 8 and 9l The switching relay 50 upon energizing,

slow action, and keeps its various armatures closed for .an appreciable period. A circuit will therefore result for the vert-ical magnet '60 from ground at armature 56 of the switchin'g relay by way of armature 23 of the slow acting release relay.l The vertical magnet operates and causes the line wipers l and 3 to i engage thecorresponding line contacts of the seized trunk, whereupon lthey will be locked mechanically as described. l

The fl'irtherl operations of the switches l taking place in extending a call are identical' again and shall Vbe described together. The' lineand vreleas'e'relays of the switch, on the seized trunk line--(sel ector, connector or repeater, as the lclase may be)--energize now and theflatter places ground on the associated release trunk conductor, 'which ground is extended back throughl the private wiper of the selector inquestion and armature 52 off the switching relay` to the release trunk conductor 9 before the slow acting release relay 20 has had time-to deenergize and to removev local ground from the release trunk at'its armature 21. This,`of course, is the usual holding circuit .which is established when one automatic switch seizes another and cuts through. The calling subscriber now proceeds to dial the remaining digits in the desired number, thereby setting up the connection through a connector switch or through another selectorl and a connector switch, as the case maybe. In any event the selectors shown perform no other operation until the calling partly replaces the receiver.

When the receiver is replaced at the calling substation, the ground potential is removed from the release trunk by the connector switch in use-(or by a repeater or similar circuit in other cases)-whereupon the n switching relay 50 deenergizes. The release operations of the two switches'differ slightly and I shall therefore consider them separately. i y

In the selector, Fig. 7 the switching relay 50'7upon dcenergizing, o-pens its armature 53, and disconnects thereby the additional magnet 90, which causes the line wipers l and 3 to ret-urn to normal movement commences.

withdraw from theline contacts in the bank and to assume their normal position between two adjacent levels as described. At armature 54, the switching relay 50 closes a circuit forthe release magnet by way of armature ll of the line relay, armature 22 of the release relay and off normal springs G. The release magnet 80 energizes now and restores the switch to its normal position as usual.

It should be observed that the opening of the two magnets, i. e., the magnet will deenergize and cause the removal of the line wipers from the line contacts before the energization of the release magnet can possibly v actuate the release mechanism, it 'will be evident that anl adjustment between the two arf matures 53 and 54, causing the first to open before the latter closes can easily be effected and will preclude vany possibility of trouble. In other words, the adjustment of the mechanism must besuch that the line wipers are withdrawn from the line contacts before tble c difficulties will be experienced in bringing about the proper functions, simply due to the dieren'ce in mechanical inertia of the various moving parts, as I have intimated above, as it is obvious that the moment of inertia ofthe wiper carrier is less than that of the entire shaft including the wipers. 'Ihe Iwipers will therefore follow the operation of the magnet 90 quicker than the shaft can follow the energization of the release magnet. The adjustment of the two contacts will therefore be more of a character of additional precaution.

-In the switch illustrated in Fig. l1, switching relay 50 upon deenergizing closes armature 54 and completes thereby the circuit for the releasemagnet 80. The withdrawal of .the line wipers from the line contacts and the lowering of the tension of the private wiper takes place as described, and the switch is then restored to normal position as usual. The circuit of the release magnet is opened at the associated off normal springs 6 as soon as the shaft assumes its normal position.

The selector is now at normal and in readiness to be used in completing a subsequent connection. v

In Figs. 12-15, inclusive, I have shown a new type of operating magnet. As will be remembered from the brief account given previou'sly, the novelty resides in the arrangement of the adjustable heel piece and in using :,casnac solid cores. The manifestation of eddy currents isthereby reduced to a minimum, preventing destruction of the magnet if connected to current for an undue period of time, and 'i its magnetic qualities are considerably im? proved. 'The magnet ma be used in place of the vertical, rotary or re ease magnet in theusual or improved type ofvertical and rotary switch mechanism shown and described in the l present case.

Referring now to the drawings, Fig. 12y is a side, and Fig. 13 a back view, showing the magnet i-n operated position with the armature attracted; Fig. 14 illustrates the magnet in normal or nonoperated position, and Fig. 15 is a sectional view`. It will be seen that the heel-piece consists of two parts designated through the numerals land and held-together by means of screws 3 and 4. The lower heel piece is provided with longitudinal slots 5 and 6, for the purpose of allowing convenient adjustment of the upper part of the heel piece. The laminated core 7 is riveted at the lower end to a' mounting plate 8, which is' rigidly7 secured to the lower angular part of the heel piece by means of counter sunk screws, as is indicated at 9. The core 7 serves as a center for the winding of coil 10 which is protectedat itsupper and lower end by the usual insulators 11 and 12, and terminated by a heavy insulating 13. The magnet may be mounted in the usual manner on the switch frame or other arts, the purpose it is inten ed'to depending upon serve. The armature 14 is brought into relation with the magnet as shown in the drawings and is pivoted on pins 15 and 16, mounted on the'switch'frame at 17-and 18.

Referring now particularly to Fig. 14.

After mounting the magnet in its proper place, the required air-gap will be adjusted. by inserting the usualthickness gauge between armature and core and connecting the magnet to current. Accordingly, the magnet energizes and attractsits armature 14 and the movable part 2 of the heel piece pulls up also,

the screws 3 and 4 not being tight at this mobe taken up by the heel piece without any iit i The magnet is now adjusted and ready ment. The heel` piece attaches itself at its upper end to a point atv the inner surface of the armature. The-screws will be tight now securing the heel piece in its proper positipn.

or operation. In energizing the magnet will appear as shown in piece closely engaging the armature.

. The adjustable heel piece has several advantages. In the first place, rendered extremely simple because any vanations in the size o the core or armaturewill ting, which is of particular advantage in case of radjustments;. secondly, the mechanical parts are made easily accessible; and thirdly, the magnetic properties oi the magnet are 2, respectively,"

' ing` a vertically plate Figs. 12 and 13 with the heel adjustment. is Y proving lthe magnetic properties of the magi net. A

vIt will be apparent from the foregoing description that 1 have devised several improvements'applicable to switching mechanisms used in telephone signaling and allied systems, rendering the apparatus reliable in use, cheapening the process of production and answering all requirements set for safe and economical operation. I desire it to be understood that the manner of carrying out my invention as shown in the drawings is by way of example only and that I do not want to be limited in the application ofthe disclosure.

What I consider new shall be'pointed out in the. following claims.

. Whatis claimed is:

1. lAn automatic switching mechanism havand horizontally movable shaft provided with a pair of wipers, terminals` arranged in horizontal rows accessible to said wipers, means for advancing' said wipers along said terminals but out of engagement therewith, to select certain of said terminals, and means for then moving said wipers in a direction lonm'tudinallv to said shaft to engage the selected terminals.

2. An automa-tic switching mechanism having a vertically and horizontally movable shaft provided with a pair of wipers, terminals arranged in horizontal'rows accessible to said wipers, means for advancing'said wipers along said terminals but out of engagement therewith, to select certain of said terminals, and means for then moving said wipers independently of but in a direction longitudinally to said shaft toengage the selected terminals.

3. An automatic .switching mechanism having a vertically and horizontally movable shaft` provided with a pair of wipers, terminals arranged in horizontal rows accessible to said wipers, means for advancing said wipers along said gagement therewith, terminals, able upon certain of said terminals beingv se1ected,' for moving. said wipers independently of, but in a direction longitudinally to said shaft, y to engage said selected terminals.

4. Anautomatic switching mechanism having a vertically and horizontally movable to select certain of said terminals but out of enand electromagnetic means operiso , shaft provided with a pair of wipers, terminals arranged Ain horizontal rows 'accessible to said wipers, means for advancing -said Y wipers along saidterminals but outof enative upon and during the seizure of certain gagement therewith, to select Certain of said terminals, and electromagnetic means opernally to said shaft to engage the selected terminals.

5. -An automatic" switching mechanism having a vertically and horizontally movable shaft' provided with a pair of wipers, terminals arranged in 'horizontal rowsv accessible vto said wipers, means for advancing said wipers lalong said terminals but out of en- I I gagement therewith, to select certain of said switch having a shaft provided with a pair.

terminals, and electromagnetic means eiec'- tive upon certain of said terminals being selected for causing said wipers to engage said terminals, and :tor locking ated position.

saidwipers4 in oper- 6. An automatic switching mechanism having a verticallyand horizontally movable shaft provided with a pair of wipers, terminals arranged in horizontal rows accessible'to said wipers, means for advancing said wipers alongsaid terminals but out of erigagement therewith, to select certain of said terminals, and electromagnetic means oper- -ative upon the seizure of certain of said terminals for moving said wipersin a vertical direction to cause said wipers toengagesaid terminals, and to lock saidwipers in operated position. f

7. An automatic progressively movable of.,wipers, terminals arranged in groups in horizontal rows, a first electromagnetic means for moving said wipers in a vertical plane to select a group, a second electromagnetic means for moving said wipers 1n `a horizontal plane underneath said terminals but out of,4 engagement therewith, to select certain of said terminals, and a thirdl electromagnetic meansfor then moving said wipers to engage i the 'selected terminals.

- of wipers, terminals arranged in groups lin lected terminals.

8.' An automatic progressively movable switchhaving a shaft provided witha p'air horizontal rows, a first electromagnetic means for moving said wipers` ina vertical plane to select a group, a second electromagnetic means for moving saidwipers in a horizontal 'plane underneath said terminals but out offenga'gem'e'nt therewith, to vselect-,cer-` tain ofsaid terminals, vand a third Velectromagnetic means for thenv moving said wipers independently of said shaft toengage the se- 9. An automatic progressively .movable vswitch having a shaft provided with a pair of wipers, terminals arranged ingroups in horizontal rows, a first electromagnetic horizontal rows,

means for moving said'wipers in a vertical moving said wipers into engagement therewith and for keeping said'wipers in operated position.-

10. An automatic progressively movable switch having a shaft provided with a pair of wipers, terminals arranged in groups inhorizontal rows, a first electromagnetic means for moving said wipers in a vertical plane toselecta group, asecond electrom-agnetic means for moving said wipers in a horizontal plane underneath said terminals but out of engagement therewith, to select certain of said terminals, and means effective upon seizure of said terminals Vfor moving locking said wipers in operated position.

11. An automatic progressively movable switch having a shaft provided with a pair of wipers, terminals arranged in groups in a first electromagnetic means for moving said wipers in a vertical plane vto select a group, a second electromagzontal plane underneath said terminals but out of engagement therewith, to select certain of'said terminals, and means for movingrv said wipers into engagement with the selected terminals, and for locking said wipers in operated position.

12. -An automatic progressively movable switch having a shaft provided with a pair of wipers, terminals arranged in groups in horizontal rows, a i'irst electromagnetic means for moving said wipers in avertical plane to and after the seizure of said terminals for said wipers to engage said terminals, and for 'netic means for moving said wipers in a horiiou v select a group, a second electromagnetic means for moving said wipers in a horizontalplane underneath said terminals but out of engagement therewith, to select certain of said terminals, and means for moving said wipers to. connect withthe selected terminals and for withdrawing said wipers during ,the restoring operation of said switc 13. :An automatic progressively movable switch having a shaft provided with a pair of wipers, terminals arranged in groups in horizontal rows, a first electromagnetic means for`moving said wipers in a vertical plane to selecta group, a second electromagnetic Vmeans for moving said'wipers in a horizontal plane underneath said terminals but out of engagement therewith, to select 'certain of said terminals, and separate means independent osaid shaft/and said velectromagnetic .means for causing said wipers to engage the selected terminals and for withdrawing said wipe'ills during the restoring operation of said swite iso. i'

14. An automatic remotely controlled switching mechanismliaving a'movable'mem-y ber p'rovidedwith wipers, terminals associated with trunk lines provided for transmitting. electric energy thereover, -said terminals being arranged in physical sequence in rows, means for advancing s aid wipers parallel to and between two adjoining'rows of terminals but out of engagement therewith, to select certain of said terminals, and means for then moving said wipers toengage the selected terminals.

15. An automatic remotely controlledswitching mechanism having a movable member provided with wipers, terminals associated with v"trunk lines provided for trans mitting electric energy thereover, said terminals being arranged in physical sequence in rows, means for advancing said wipers parallel to and between two adjoining rows of terminals but out of engagement therewith, to select certain of said terminals and means `for then moving said wipers independently.i

of said movable member `to engage the selected terminals.

16. An automatic remotely controlled switching mechanism having a movable mem- -ber provided with wipers, terminals associated with trunk lines provided for transmitting electric energy thereover, said terminals being arranged in physical sequence in rows, means for advancing said wipers parallel toand between two adjoining rows of terminals but out of engagement therewith, to select certain of said terminals, and separate means for then moving said wipers independently. of but longitudinallyto said movable member to engage the selected terminals.

17. An' automatic remotely controlled vswitching mechanism having a movable member provided with wipers, terminals associated with trunk lines provided for trans-v mitting electric energythereover, said terminals being arrangedl in physical sequence in rows, means for advancing said. wipers parallel to and between-two adj oiningrows of terminals but out of engagement therewith, to select certain of said-terminals, and means for moving said wipers to engage the selected terminals only when needed for transmitting current thereover.

18. -An automatic ,remotely controlled switching mechanism having a movable member provided with wipers, terminals associated with trunk lines provided for translmitting electric 'energy thereover, said terminals being arranged in physical sequence in rows, means for advancing said wipers parallel to and between two adjoining rows of terminals but out of engagement therewith,

toselect certain of said terminals, and means l for moving said wipers to engage the selected terminals only when needed for transmitting energy thereover, and withdrawing said wip-l ers. -during the restoring' operations of lsaid. switching mechanism.. f

. 19. An automatic: remotelyfcontrolled switching mechanism having a movablemember provided with wipers, terminals-associated with trunk lines provided for transmitting electric ener thereover, said'terminals being-arrange in physical seqiience in rows, meansfor 'advancin of terminals but out of engagement therewith, tofselect certain of said terminals, and means for moving said wipers to. engage the selected terminals only when needed for transmitting energy.thereover, and for locking said wipersy wipers said wipers l f parallel' toand between two a joining rows plurality of wipers, i

underneaththe terminals in said row but out of engagement therewith,- to select said desired terminals, and automatically operated means to move said wipers to connect with said selected terminalsonly when needed for transmitting energy thereover. 21. A remotel controlled switching device having 4a mova le member, a vplurality of brushes secured to said member; a lurality o-terminals associated with trunk lines provided for transmitting electric energy thereover, said terminals being arranged in physical sequences in rows, meansfor o erating said movable member. to advance sai brushes parallel to said'terminals but out of engagement therewith to select certain .of said termi- ,nals, and means for moving -said brushes to engage the selected terminals onlywhen need- ;"ed for transmitting ener thereover.

122. A remotely control edl switchin device having a movable member rovide with a lurality, of brushes, a plura ity of termi-4 na s associated with trunk lines provided for transmitting electric energy thereover, said terminals being arran e inph sical seilo quence infrows accessi le to sai brushes, means for o erating said movable member to but out of engagement therewith to sition `said brushes opposite certain of'sai termi- `advance sai brushesparallelto'said terminals nals, and.` means for then displacingsaid ,brushes relative to said movable .member and in a direction longitudinal the selected terminals.

23. A switching mechanism having a movable 'shaftprovided withone test and two line wipers, terminals associated with trunk lines arranged in groups in horizontal rows accesv thereto to Vengage sible to said wipers, one test terminal and two Y line terminals representing a trunk line, the

test'and the line terminals of a group being i located intwo separate rows in physical sequence, and means oradvancing said wipers over' said terminals y to select an idle f trunk line. f' f 24. A switching mechanism having a movable shaftprovded with one test and two line i wipers-,';:;t'est. .and line terminals associated with-trunk lines arranged in groups in horizontalrows accessible to said wipers, the testand the line terminals of a group being located-intwo separate'rows. 1n physical sequence,

each; trunk having a test terminal in a test row and'two adjoining line terminals in the:corresponding` line row, and means for moving .said wipers into engagement with a Y desired set oft-erminals. f

25,; A switching mechanism having a movable shaft, a pair of wipers, mountedl on aI lU-sha'ped carrier secured to said shaft and provided with fa fan-like extension, a rod locatedin front of and longitudinally to said shaft and provided at its lower end with a plurality .of projections, terminals arranged in groupsl in, horizontal rows, means for moving said shaft axially to position said wipers s relativeV to a certain. group of terminals,

"f means'for then moving said shaft radially to advance the'wipers towards certain terminals within said row but out of engagement therewith, while the fan-like extension of said carrier advances between two projections ofsaid rod correspondin to the selected group, andmeans foroperating. said rod to causel a displacement of said carrier in a directionflongitudinal to said shaft to move said wipers into engagement with 'the selected terminals.

26.' yA switchin mechanism having a movable1 shaft, .a U-s aped member carrying at one end a pair of wipersand provided at its other end with a fan-likesegment, means' for fasteningsaid `member to said shaft, in

cluding a clam-p provided with aprojectin arm carrying a pin extending through sai segment, said shaft extendingthrough the legs 'of said member and through said clamp, .a helically wound expansion spring inserted between said clamp and one leg of said member, terminals arranged in groups in horiprovided on said rod, for causing avlongitudinal displacement of said member to move said wipers into engagement with the selectedv terminals.

27. yA switching mechanism having a movableshaft carrying a member longitudinally movable relative to said shaft and provided with a pair of Wipers at one end and a projecting guide segment atvthe other end, said wipers being radially displaced by 180 degrees relative to said segment, terminals arranged in groups in horizontal rows, a movable rod located in front of and longitudinally to said sha-ft and provided with a plurality of guide notches, each notch corresponding to a certain row, meansior moving said shaft axially to position said wipers opposite a desired row and to position said guide segment opposite a guide notch corresponding to said row, means for then moving said shaft radially to advance -said wipers towards certain terminals within said row but out of engagement therewith and to advance said guide segment within said guide notch, and means for moving said rod to cause said wipers to engage the selected terminals.

28. An automatic switching mechanism, having a'movable member provided with wipers, terminals being arranged in physical sequencein rows, means for advancing said wipers Aparallel to and between two adjoining rows of terminals but out of engagelment therewith, to select certain of said terminals, and means for then moving said wipers to engage the selected terminals.

29. A two-directional step-by-step switch in which the wipers are adapted to be voperated in three stages, first in one direction and then insecond direction and finally in a direction parallel to the first direction.

v 30. A two-directional automatic switch comprising a shaft carrying wipers adapted to move axially and to rotate to engage terminals arranged in horizontal rows in which the wipers are rotated lparallel tov said llerminals but out of engagement therewith to select a particular'set of terminals and then in a direction parallel to the axis of said A shaft to engage a particular set of terminals.

31. A step-by-step automatic switch in Iwhich a plurality of sets of terminals are arranged in'rows with the terminals ot a set adjacent to each other and in which the switch wipers are advanced parallel toand between two rows but out of engagement with said terminals of a `selected set and finally moved 1n a planete establish connection-with the terminals .ofthe selected set.

321A step-by-step automatic switch having wipers and a plurality of sets of terminals arranged in rows with the terminals of aset adjacent to each other, means for'moving the wipers of the switch in one direction vopposite to al particular set of terminals,

Lerminnls, means for moving said wipers in another direction in the selected space but 10 out of engagement with the terminals, and means for causing the wipers to again move in the first direction to engage said-terminals In witness whereof, I hereunto subscribe 15 my name this 9th day of September, A. D., 1925.' i

JOHN ERICKSON. 

